Prefabricated flight deck structure for offshore drilling platforms

ABSTRACT

A prefabricated flight deck is mounted on a framework above an offshore drilling platform to accommodate the landing of aircraft thereon. The flight deck has a plurality of lightweight honeycomb-type panel sections each formed of outer and inner skin members with honeycomb core and reinforcing beams sandwiched between the skin members and provided with lift stations. The panel sections are united together at complementary stepped joint surface areas which are both adhesively joined and mechanically fastened at spaced intervals to form an integral unit which is covered with an outer protective layer forming a sealed nonporous top surface. In a preferred form the deck is generally polygonal in shape and the panel sections are pie-shaped and extend radially with truncated inner ends thereof forming a central opening. A round center panel section fills the center. A safety fence projects outwardly from the outer ends of the panel sections for added surface area beyond the prefabricated deck.

United States Patent 1191 Bain [75] Inventor: Billy R. Bain, Arvada, C010.

[73] Assignee: Levingston-Armadillo, Inc., Arvada,

[22] Filed: Nov. 22, 1971 [21] Appl. No.: 200,886

[52] U.S. Cl 52/73, 52/237, 52/125, 52/617 [51] Int. Cl E04b 5/43 [58] Field of Search 52/73, 126, 125, 122, 618, 52/615, 584, 582, 299; 61/46, 46.1; 175/9 [56] References Cited UNlTED STATES PATENTS v 1,571,484 2/1926 Knight 52/586 2,412,242 12/1946 Beaud 1 52/593 2,453,326 11/1948 Lambert 52/615 2,922,299 1/1960 Deam 52/125 3,236,014 2/1966 Edgar 52/593 3,277,620 10/1966 Martin 52/586 3,354,590 11/1967 Gilroy 52/299 3,456,720 7/1969 Brewer..... 175/8 3,529,393 9/1970 Wilkins 52/618 3,628,336 12/1971 Moore 61/46.5 3,633,325 l/l972 Bartoli 52/73 3,636,667 1/1972 Walz 52/79 June 11, 1974 3,657,895 4/1972 Phelps 175/9 3,680,273 8/1972 Bigelow 52/122 3,699,688 10/1972 Esters 175/9 Primary Examinerl'lenry C. Sutherland Assistant Examiner-Henry Raduazo 5 7 ABSTRACT A prefabricated flight deck is mounted on a framework above an offshore drilling platform to accommodate the landing of aircraft thereon. The flight deck has a plurality of lightweight honeycomb-type panel sections each fonned of outer and inner skin members with honeycomb core and reinforcing beams sandwiched between the skin members and provided with lift stations. The panel sections are united together at complementary stepped joint surface areas which are both adhesively joined and mechanically fastened at spaced intervals to form an integral unit which is covered with an outer protective layer forming a sealed non-porous top surface. In a preferred form the deck is generally polygonal in shape and the panel sections are pie-shaped and extend radially with truncated inner ends thereof forming a central opening. A round center panel section fills the center. A safety fence projects outwardly from the outer ends of the panel sections for added surface area beyond the prefabricated deck.

16 Claims, 9 Drawing Figures PATENTEUJUHI 1 1914 3.815300 SMEI1IJF3 INVE TOR BILLY R. A/N

By K I ATTORNEYS PATENTEUJUH n 1914 3515300 SHEEI 3 0F 3 PREFABRICATED FLIGHT DECK STRUCTURE FOR OFFSHORE DRILLING PLATFORMS This invention relates to flight deck apparatus for landing and take-off of aircraft and more particularly to novel and improved lightweight flight deck structure for offshore drilling platforms and the like.

Offshore drilling platforms for drilling and pumping 'underwaterwells support a drilling rig and the necessary equipment and personnel loading for operating same. Some offshore drilling platforms have a power unit to propel the platform to the point of destination and extensible and retractable jack-type legs to anchor the platform to the floor of a body of water. The large amount of personnel and equipment are required for continued operation of drilling rigs which necessitates prompt and efficient'transportation' of cargo to and from the platform. Of particular importance is theability to establish aircraft flights to and from the drilling platform with safety and ease of take-off and landing especially during high winds. Some attempts have been made to provide steel flight deck structure on the platform but the loading capacity of a floatingplatform structure severelyjlimits the size of a steel deck. In an application entitled Prefabricated Building Structure For Off-Shore Crew Quarters and The Like, Ser. No.

792,475, now U.S. Pat. No. 3,636,667 assigned to the assignee of the present invention, thereis described a prefabricated flight deck forming the roof of the building structure.

Accordingly, it is an object of this invention to provide a novel and improved prefabricated sandwich-type flight deck structure for offshore drilling platforms and the like.

Another object of this invention is to provide a novel prefabricated flight deck assembly mounted on a structural-framework which projects laterally out and away from the usable or working surface of the platform so as not to unduly occupy or materially interfere with the platform, thereby avoiding danger to aircraft and personnelof landing on the platform.

A further object of thisinvention is to provide a novel prefabricated flight. deck made up of prefabricated honeycomb core-type panels, which are substantially lighter than structural steel flight. deckstructures.

Yet another object of this invention is to provide a prefabricated flight deck structure characterized by ease of fabrication and assembly at the point of intended use and is readily mounted at different desired levels either directely on the platform or on a derrick on the platform.

Yet a further object of this invention is to provide a novel prefabricated flight ceck which mounts directly on a horizontal framework and is made up of lightweight prefabricated panels united together to form an integral unit which is covered with an outer protectiv layer to form a sealed non-porous surface.

In accordancewith the present invention in-a preferred form shown, a prefabricated flight deck assembly-is mounted-on and affixedto a support framework above the platform, the support framework projecting horizontally beyond a side edge of the platform. The

flight deck is made .up of a plurality of prefabricated panel sections mounted on and projecting horizontally beyond the support framework, the panel sections having complementary stepped joint surface area joined by an adhesive, together with fastener members extending I 3,815,300 r v through beams along the joint surfaceareas at spaced intervals to form an overlapping joint. A preferred form shown is of a generally polygonal shape and is made up of radial pie-shaped panelsection-s and a circular center panel section. Each panel section has a plurality of spaced lift stations to facilitate its being lifted into position by a crane or the like for the assembly thereof. Each panel section is composed of upper and lower skin members, preferably woodemwith honeycomb core and reinforcing beams sandwiched between the skin members. An outer protective layer, preferably fiberglass, covers the exterior surfaces of the joined panel sections to form a sealed non-porous top layer on the deck. Outrigger or safety fence structure is attached to the periphery of the deck to provide increased surface area. Other objects, advantages and capabilities'of the present invention will become more apparent as the description proceeds taken in conjunction with the accompanying drawings, in which: FIG. 1 is a side elevational view of a jack upoffshore drilling platform having a prefabricated flight deck structure embodying features of. the present invention mounted therein; i FIG. 2 is a top plan view deck assembly of FIG. 1; FIG. 3 is a sectional view taken along lines 15-15 of of the prefabricated flight- FIG. 2 showing a joint of the deck assembly along adjacent of the side edges of the radial panel sections;

FIG. 4 is a sectional view taken along lines 44 of FIG. 3 showingthe manner of fastening the deckassembly to the support frame beams at a joint; I FIG. 5 is a top plan view of one of the pie-shapedradial panel sections of the flight deck assembly shown in FIG. 2; a

FIG. 6 is a sectional view taken along lines 66 of FIG. 5 showing the details of the lift or pickup points for each radialpanel section; I

FIG- 7 is a top plan view of the center panel section for the flight deck assembly shown in FIG. 2;

FIG. 8 is a sectional view taken along lines 8-8 of FIG. 7 showing a joint between the radial panel sections and the center ,panel'section; and I FIG. 9 is an enlarged side elevational view showing the connection of the outrigger structure tothe deck assemblyshown in FIG. 2.

Referring now to the drawings, in FIG. 1 thereis shown a jack-uptype drilling rig designated generally by numeral 10 comprising a floatable platfonn 11 car: rying equipment used for offshore drilling operations and typically includes upright derricks l2 and 13, a jack house 14, a crane {boom 15, a control house 16 and the like. The platfofm 11 is provided with a propulsion unit 17 at the rear to propel it through the water "to a desired location. A plurality of extensible and re: tractable jack-up leg units 18 depend from theplatform and are extensible to a selected depth to secure or an:

chor the rig to the floor of a bodyof water at the de- :sired location. For the type shown mechanical gearrnotors and gears with suitable controlsare used to advance and retract the legs. Thejack-up assembly of the type shown is capable of anchoring the platform in up to 300 feet of water. The configuration of the platform 11 (as viewed in the plan) maybe generally triangular,

. rectangulan'or of other desired shapes. In the triangular form the jack-up'leg uni'ts 18 are. disposed inwardly of each apex or corner to form a balanced support for the platform. I

A cantilever-type steel support framework 21 mounts at the edge of the platform. It is understood, however, that the support framework may mount on a derrick on the platform if required. As best seen in the side elevational view, .thesupport framework 11 includes a lower section 22 madeup of interconnected spaced upright columns and an upper section 23 made up of horizontally disposed spaced beams disposed in a common horizontal plane. These upper and lower framework sections 22 and 23 have an inner part-directly above the platform and an outer part projecting outwardly from a side of theplatform over the water to give the cantilever effect. As viewed in plan, the upper section 23 is generally of a polygonal shape and includes spaced parallel longitudinal beams 24 at right angles to the side edge of the platform, spaced parallel transverse beams 25 connected to the longitudinal beams, and periphery beams 26 which join the ends of adjacent of the longitudinal and transverse beams. The upper truss section 23 shown is'essentially an eleven-sided configuration figuration with the two sides closest to the platform being made as one side extending parallel to the side I edge of the platform and by bolts or the like. i

The prefabricated flight deck assembly 30 is mounted on the upper horizontal section 23. This prefabricated flight deck assembly 30 shown is of a generally polygonal shape and is made up of a plurality of generally. pie-shaped radial panel sections 31 having the inner ends cut off or truncated and a prefabricated center panel section 32 which fits into a central aperture formed by the truncated ends of an assembly of the pie-shaped panel sections. Outrigger structure 33 in the form of a safety fence projects outwardly from the outer edge of the pie-shaped panels to provide added surface area beyond the prefabricated part of the deck.

are suitably fastened thereto Each pie-shaped radial panel section 31 comprises upper and lower skin members 35 and 36, respectively, eachmade of plywood or the like having an inner honeycomb core 37 and wooden reinforcing beams sandwiched between the skin members which extend throughout the entire length of the skin members. The reinforcing beams include side beams 38 and 39, an inner end beam 41 and an outer beam 42 which together form a peripheral frame. The side beams 38 and '39 have outer end portions 38 and 39', respectively,

which projectbeyond the outer ends of the skin members and inner core, and inner end portions 38" and 39" respectively, which project beyond the inner ends of the skin members. Adjacent side beams are fastened together at both inner and outer ends as described more fully hereinafter. The reinforcing beams preferathe honeycomb core as shown in FIG. 4 but the details of the core has been omitted from the other Figures for clarity.

Lift stations generally designated 45, 46 and 47 are provided at three different points on each radial panel section 31 to facilitate the lifting thereof by an overhead crane or the like. Outer lift stations 45 and 46 are located inwardly of the wider outer end and spaced from one another and the inner lift station 47 is located inwardly ofthe narrower inner end for a balanced three-point lift capability. Each lift station is defined byreinforcing the panel section with twojgroups of spaced pairs of intermediatereinforcing beams 48 and 49 exand internal threads extends-up throughor telescopes in the tubular member 51. Housing 52 is fastened along the underside by bolts 53 which thread into the adjacent intermediate reinforcing beams 48 and 49. The heads of the bolts 53 are recessed in the lower skin member. An externally threaded eyebolt54 threads into the internal threads in the flanged housing 52 and a cable or the like depending from the crane boom is suitably secured to each eyebolt to lift the panel into place on the framework in the assembly'thereof.

As best seen in FIG. 3, an outer timber38amakes up a part of theentire side beam on one sideof each radial panel section 31. Timber 38a'is approximately half the vertical extent of two other inner sandwiched timbers 38b and 380 which extend the full height of the core to form an inwardly stepped joint surface area which is complementary to that of the adjacent radial panel sec tion having the outer timber 39a in an offset position relative to timber 38a and secured to inner sandwiched timbers 38b and 38c. The abutting joint surfaceareas are secured together by an adhesive along a glue line represented at 56. Fasteners 57 in the form of bolts are disposed at spaced intervals along the joint and extend downwardly and are angularlyv inclined laterally with each bolt extending through the upper-skin member and both narrower timbers of the abutting laminated beams to draw the stepped joint surface areas together along the glue line. For the deck shown the fasteners 57 are located at two-foot intervals. The head of each fastener 57 is recessed or countersunk into the outer skin member 35 and in the assembly of the panel section this recess is filled with a resin paste 58 or the like.

The inner ends 38" and 39" of a pair of abutting panel sections 31 are further fastened by a pair of bolts 590 which pass transversely therethrough and in turn the outer ends 38' and 39' are fastened by bolts 59b for added strength.

The center panel section 32 closing the center area of the deck comprises a-generally circular outer skin 1 member 61, a circular inner skin member 62 ofa lesser diameter than the outer skin member, and a honeycomb core 63 and side reinforcing beams 64 sandwiched between the inner and outer skin members, the outer side reinforcing beams 64 being sandwiched between the inner and outer skin members. The outer I side reinforcing beams 64 are made of two timbers lamtwo laminated timbers are spaced from the outer side beams to form a space 67. The glue line for the joint between the radial panel section and center panel section is represented at 70. This center panel section provides an assembly which is readily inserted into the central aperture of the assembly of pie-shaped members and is secured thereto by an adhesive and three spaced bolt fasteners 68 which extend vertically down through the beams of the center panel and into the radial panel sections 31, the heads of the fasteners being recessed in the outer skin member and filledwith a paste 58.

The assembly of pie-shaped panels and center panel section making up the deck are provided with an outer protective coating or layer 69 which covers all of the exposed surfaces defining an essentially seamless nonporous top deck surface. The top deck surface is preferably fiberglass material which may be, sprayed or otherwise applied in a bonded relation to the outer skin of the panels and may be applied to a desired thickness. As employed therein, the term fiberglass has specific reference to glass fibers bonded together as a suitable bonding agent such as a synthetic resinous compound which is applied to the prefabricated panel sections and will cure into a firm bonded relation to the underlying surface.

The outrigger structure or safety fence 33 is made up of a series of interconnected box-shaped side frame members 71 and inner and outer corner frame connectors 72a and 72b arranged along the outer periphery of the deck. The side frame members comprise an inner bracket 73 having a generally right-angle cross-section which fits against the upper outer corner of the deck and is secured thereto by a top and outer fasteners 74 and 75, respectively, shown as being bolts whichthread into the wooden beams. A main tubular portion 76 ex tends outwardly and upwardly at a slight angle from each bracket 73. Inner and outer tubular portions 77 and 78 connect at the inner and outer ends of the main tubular portion and to a next adjacent main tubular portion 76 to form a boxshaped framework. The outer corner frame connectors 72b provide extensions for tubular portion 78 and the inner corner frame connector is disposed outwardly to inner tubular portion 77 to accommodate the corners of the polygonal shape. The conncted frame members 71 and 72 are covered with a layer of galvanized wire 79 such as chain link and a top layer of fabric 80 such as canvas is laced over the wire or the like.

As best seen in FIG. 4, the prefabricated deck is fastened to the support framework beams by a holddown fastener in the form of a bolt 81 which extends down through tubular members 82 in each beam panel section and through atop truss beam 24. The tubular members preferably are of a PVC material or the like and the heads of the bolts are recessed in the top skin member so that after assembly the recesses are filled with a resin 83 prior to applying the outer protective layer. The fasteners 81 are located at spaced intervals where the joints of the deck overlay a top support truss beam.

A prefabricated deck utilizing the fiberglass sandwich panel above described is of substantially less weight than that of comparable steel flight decks. For example, a prefabricated deck made in accordance with the present invention had approximately twice the surface area of that of steel deck for the same weight. This is an increase in the loading strength to deck weight of about two to one, affording a significant ad vantage over comparable steel flight decks for floating platform applications.

While a generally circular or polygonal deck configuration is shown, it is understood that the present invention is also applicable to rectangular deck shapes using an assembly of rectangular panel sections.

Although the present invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made by way of example and that changes in details of structure may be made without departing from the'spirit thereof.

What is claimed is:

1. In a flight deck structure for an offshore platform and the like for the landing and take-off of aircraft, the combination comprising:

a cantilever support framework mounted above and projecting outwardly in a horizontal direction beyond the platform,

a prefabricated flight deck assembly mounted on said support framework including a plurality of prefabricated panel sections united together to form an integral unit, each panel section including upper and lower skin members and a honeycomb core and reinforcing beams sandwiched between said skin members, adjoining sides of said panel section having complementary stepped joint surface areas secured together with an adhesive to form an overlapping joint, fastening members extending through the stepped joints at spaced intervals along each joint to further hold abutting panel sections together, an outer protective layer covering the exterior surfaces of said joined panel sections to form a sealed, non-porous upper deck surface, and

lift station means including spaced points of support for each said panel section, each point of support being defined by a pair of reinforcing beams sandwiched between said skin members, a tubular member extending vertically through the panel between the beams, and a flanged member with internal threads telescoping in the tubular member adapted to threadingly receive an eyebolt.

' 2. In a flight deck structure as set forth in claim I wherein said framework includes a network of horizontal beams arranged in a preselected configuration to which the deck assembly is fixedly secured, said deckassembly projecting horizontally and outwardly beyond said support framework.

' 3. In a flight deck structure as set forth in claim 1 wherein said panel sections are preshaped, said skin members and beams are wooden and said outer layer is fiberglass.

4. In a flight deck structure as set forth in claim 1 wherein said panel sections and skin members have inner and outer ends and said reinforcing beams extend beyond the outer ends of the skin members, and fastening members passing transversely through both the inner and outer ends of abutting panel sections to fasten abutting panel sections together along the side edges thereof.

5. In a flight deck structure as set forth in claim 1 wherein said fastening members for the stepped joints are in the form of bolts extending downwardly and are angularly inclined laterally between abutting reinforcing beams of each of the adjacent panel sections, the upper head end of said bolts being recessed in the panel section and the recess covered with a sealing filler material.

6. In a flight deck assembly as set forth in claim 1 wherein each said panel section has lift station means to facilitate its being lifted into place on the support framework.

7. In a flight deck assembly as set forth in claim 6 wherein said lift station means are at three spaced points in a triangular configuration on each panel section.

8. In a flight deck assembly as set forth in claim 1 wherein each said panel section has tubular members extending vertically therethrough and in sealed relation to the skin members, honeycomb core, and outer layer to slidably receive fasteners to facilitate the fastening of the deck to the support framework.

9. In a flight deck assembly as set forth in claim 1 wherein said panel sections are essentially pie-shaped having truncated inner ends and extending radially and outwardly from the inner ends, and a center panel section united to the inner ends of the radial panel sections to form a generally circular deck structure.

10. In a flight deck structure as set forth in claim 1 wherein said support framework is of the cantilever type and projects outwardly from a side edge of the platform to dispose a substantial portion of the flight deck over the water, and said deck assembly projects horizontally beyond said support framework.

11. In a flight deck structure for an off-shore platform and the like for the landing and take-off of air draft, the combination comprising:

a cantilever-type support framework including a network of connecting horizontal beams forming a top section of a preselected configuration and a network of connected columns forming a lower section, and

a prefabricated flight deck secured on the top section including a plurality of radially extending, generally pie-shaped, prefabricated, radial panel sections projecting horizontally beyond said support framework and a generally circular center panel section united to said radial panel sections to form an integral unit therewith, each of said radial and center panel sections including upper and lower skin members and a honeycomb core and reinforcing beams sandwiched between said skin members, adjoining sides of said radial and center panel sections having complementary stepped joint surface areas secured together with an adhesive to form overlapping joints, fastening members extending through the overlapping joints at spaced intervals along the joints of the radial panel sections to further hold abutting radial panel sections together, fastening members connecting the inner and outer ends of abutting radial panel sections together, and an outer protective layer covering the exterior surfaces of said joined panel sections to form a sealed, non-porous upper deck surface.

12. In a flight deck structure as set forth in claim 11, wherein said center panel section has a lower skin member of lesser diameter than said upper skin memher, said center panel section having a reinforcing member under said upper skin member along the side edge thereof forming a stepped joint surface area.

13. In a flight deck structure as set forth in claim 12 including fasteners extending vertically through the center panel section and into the radial panel sections at the joint thereabove to fasten said radial panel sections with said center panel sections.

- 14. In a flight deck structure as set forth in claim 11 wherein said center panel section has peripheral reinforcing beams sandwiched between the skin members forming a part of the stepped joint surface area and arranged in an annular configuration, each peripheral beam spanning a number of radial panels.

15. In a flight deck structure as set forth in claim 11 including an outrigger structure projecting outwardly from the periphery of the deck assembly for added surface area.

16. In a flight deck structure as set forth in claim 13 wherein said outrigger structure includes a plurality of box-shaped frame members having a bracket at the inner end secured direcly to reinforcing beams along the outer edges of the panel sections. 

1. In a flight deck structure for an offshore platform and the like for the landing and take-off of aircraft, the combinatIon comprising: a cantilever support framework mounted above and projecting outwardly in a horizontal direction beyond the platform, a prefabricated flight deck assembly mounted on said support framework including a plurality of prefabricated panel sections united together to form an integral unit, each panel section including upper and lower skin members and a honeycomb core and reinforcing beams sandwiched between said skin members, adjoining sides of said panel section having complementary stepped joint surface areas secured together with an adhesive to form an overlapping joint, fastening members extending through the stepped joints at spaced intervals along each joint to further hold abutting panel sections together, an outer protective layer covering the exterior surfaces of said joined panel sections to form a sealed, non-porous upper deck surface, and lift station means including spaced points of support for each said panel section, each point of support being defined by a pair of reinforcing beams sandwiched between said skin members, a tubular member extending vertically through the panel between the beams, and a flanged member with internal threads telescoping in the tubular member adapted to threadingly receive an eyebolt.
 2. In a flight deck structure as set forth in claim 1 wherein said framework includes a network of horizontal beams arranged in a preselected configuration to which the deck assembly is fixedly secured, said deck assembly projecting horizontally and outwardly beyond said support framework.
 3. In a flight deck structure as set forth in claim 1 wherein said panel sections are preshaped, said skin members and beams are wooden and said outer layer is fiberglass.
 4. In a flight deck structure as set forth in claim 1 wherein said panel sections and skin members have inner and outer ends and said reinforcing beams extend beyond the outer ends of the skin members, and fastening members passing transversely through both the inner and outer ends of abutting panel sections to fasten abutting panel sections together along the side edges thereof.
 5. In a flight deck structure as set forth in claim 1 wherein said fastening members for the stepped joints are in the form of bolts extending downwardly and are angularly inclined laterally between abutting reinforcing beams of each of the adjacent panel sections, the upper head end of said bolts being recessed in the panel section and the recess covered with a sealing filler material.
 6. In a flight deck assembly as set forth in claim 1 wherein each said panel section has lift station means to facilitate its being lifted into place on the support framework.
 7. In a flight deck assembly as set forth in claim 6 wherein said lift station means are at three spaced points in a triangular configuration on each panel section.
 8. In a flight deck assembly as set forth in claim 1 wherein each said panel section has tubular members extending vertically therethrough and in sealed relation to the skin members, honeycomb core, and outer layer to slidably receive fasteners to facilitate the fastening of the deck to the support framework.
 9. In a flight deck assembly as set forth in claim 1 wherein said panel sections are essentially pie-shaped having truncated inner ends and extending radially and outwardly from the inner ends, and a center panel section united to the inner ends of the radial panel sections to form a generally circular deck structure.
 10. In a flight deck structure as set forth in claim 1 wherein said support framework is of the cantilever type and projects outwardly from a side edge of the platform to dispose a substantial portion of the flight deck over the water, and said deck assembly projects horizontally beyond said support framework.
 11. In a flight deck structure for an off-shore platform and the like for the landing and take-off of airdraft, the combination comprising: a cantilever-type support framework including a network of connecting Horizontal beams forming a top section of a preselected configuration and a network of connected columns forming a lower section, and a prefabricated flight deck secured on the top section including a plurality of radially extending, generally pie-shaped, prefabricated, radial panel sections projecting horizontally beyond said support framework and a generally circular center panel section united to said radial panel sections to form an integral unit therewith, each of said radial and center panel sections including upper and lower skin members and a honeycomb core and reinforcing beams sandwiched between said skin members, adjoining sides of said radial and center panel sections having complementary stepped joint surface areas secured together with an adhesive to form overlapping joints, fastening members extending through the overlapping joints at spaced intervals along the joints of the radial panel sections to further hold abutting radial panel sections together, fastening members connecting the inner and outer ends of abutting radial panel sections together, and an outer protective layer covering the exterior surfaces of said joined panel sections to form a sealed, non-porous upper deck surface.
 12. In a flight deck structure as set forth in claim 11, wherein said center panel section has a lower skin member of lesser diameter than said upper skin member, said center panel section having a reinforcing member under said upper skin member along the side edge thereof forming a stepped joint surface area.
 13. In a flight deck structure as set forth in claim 12 including fasteners extending vertically through the center panel section and into the radial panel sections at the joint thereabove to fasten said radial panel sections with said center panel sections.
 14. In a flight deck structure as set forth in claim 11 wherein said center panel section has peripheral reinforcing beams sandwiched between the skin members forming a part of the stepped joint surface area and arranged in an annular configuration, each peripheral beam spanning a number of radial panels.
 15. In a flight deck structure as set forth in claim 11 including an outrigger structure projecting outwardly from the periphery of the deck assembly for added surface area.
 16. In a flight deck structure as set forth in claim 13 wherein said outrigger structure includes a plurality of box-shaped frame members having a bracket at the inner end secured direcly to reinforcing beams along the outer edges of the panel sections. 